When the context is clear, the noun following the relative clause is often omitted. The 的de phrase, thus, becomes a noun clause.
Shàng gè yuè，wǒ gē gē﹑dì dì gè mǎi le yī liàng xīn chē；gē gē mǎi de shì rì běn chē，dì dì mǎi de shì měi guó chē。
Last month, my older brother and my younger brother each bought a new car; what my older brother bought was a Japanese car; what my younger brother bought was an American car.
Wáng ：nǐ de zhōng wén lǎo shī xìng shí me ？
Wang: What is the last name of your Chinese teacher?
Lǐ ：wǒ yǒu liǎng gè zhōng wén lǎo shī ；jiāo yǔ fǎ de xìng bái ，jiāo huì huà de xìng dīng 。
Li: I have two Chinese teachers. The one who teaches grammar is (last name is) Bai;
the one who teaches conversation is (last name is) Ding.
Zuó tiān de wǔ huì，méi yǒu chī de，méi yǒu hē de，zhēn méi yǒu yì sī。
At yesterday’s dance party, there was no food and there were no drinks; it was really
 Yip, P. C., Rimmington, D., Xiaoming, Z., & Henson, R. (2009). Basic Chinese: a grammar and workbook. Taylor & Francis.